The present invention relates to an intelligent network congestion control system for controlling congestion that occurs in an intelligent network constituted by electronic exchanges and a computer and, more particularly, to an intelligent network congestion control system suitable for a case in which a plurality of electronic exchanges are connected to one computer.
In an intelligent network system constituted by electronic exchanges for performing switching connection upon reception of calls, and a computer for performing service control on the electronic exchanges, when electronic exchanges as SSPs (Service Switching Points) transmit service request messages to the computer as an SCP (Service Control Point) in large quantities in a given period, the load on the computer increases. For this reason, an intelligent network congestion control system has been proposed, in which the computer transmits a regulation instruction to an electronic exchange to regulate the transmission of service request messages.
In the conventional congestion control system, when the computer transmits a regulation instruction containing a predetermined condition to an electronic exchange, the transmission of service request messages is regulated by a gaping scheme on the electronic exchange side. That is, message transmission from the electronic exchange to the computer is regulated completely in a given predetermined period (gap). The transmission of a service request message to the computer is permitted in response to only a call received by an electronic exchange for the first time after the end of regulation. Thereafter, the next gap control is performed in the same manner as described above.
In such a congestion control system, however, it is difficult to determine the optimal gap. In addition, when one computer performs service control on a plurality of electronic exchanges, the service request messages transmitted from the respective electronic exchanges to the computer often vary in number. In this case, if the respective electronic exchanges are uniformly regulated, an expected regulation effect may not be obtained.
Under the circumstances, Japanese Patent Laid-Open No. 7-212463 discloses a congestion control system which can obtain a satisfactory regulation effect even if the service request messages transmitted from a plurality of electronic exchanges to one computer vary in number when the computer performs service control on the electronic exchanges. In this congestion control system, when a large number of service request messages are generated with respect to the computer, the computer transmits regulation instruction messages to all the electronic exchanges in accordance with the number of service request messages received. On the electronic exchange side, a regulation, e.g., decreasing the number of service request messages transmitted to the computer, is performed in accordance with the regulation instruction message.
In this intelligent network congestion control system, as the number of electronic exchanges which transmit service request messages to the computer increases, the number of regulation instruction messages transmitted from the computer to the electronic exchanges increases. Consequently, in transmitting regulation instruction messages, the loads on the computer and the lines between the computer and the electronic exchanges increase.